Sterilization of male animals, practised to limit reproduction in stray animals and livestock, is usually effected by castration. Sterilization operations involving vasectomy and vasligation are also effected on male humans.
The extreme nature of these procedures and the necessity for skilled surgical operation has led to suggestions of alternative approaches to mammalian sterilization. For example, a number of hormonal formulations, consisting of anti-androgens and androgens, have been suggested for suppression of spermatogenesis or interfering with the maturation of sperm.
In early clinical trials, these formulations, however, have exhibited adverse side effects, including, loss of libido and a dependence on a continual intake of hormonal steroids.